Reyer, Prof. E., ii. 474
Reynolds, Mr. S. H., i. 177, 179, 256
Rhobel Fawr, i. 177, 178, 186
Rhyolite, i. 19, 22, 24, 131, 161, 165, 167, 168, 178, 204, 210, 231, 232, 255, 276, 278; ii. 185, 205, 371, 424, 437
Rhyolitic conglomerate, ii. 195, 206, 429
Richardson, Rev. W., ii. 110
Richthofen, F. von, i. 28; ii. 115, 116
Rivers made to shift their channels by volcanic eruptions, i. 42, 49;
of the Tertiary volcanic period, ii. 217, 228, 231, 234, 456
Rocks, oldest known, i. 110
Roscommon, volcanic rocks of, i. 316
Rosenbusch, Prof. H., ii. 136, 137
Ross, Mr. Alexander, ii. 406, 409
Rothliegende, ii. 95
Roxburghshire, Carboniferous vents of, i. 55, 403, 404
Rubers Law, i. 375, 380, 404
Rum, i. 112;
basalt-plateau of, ii. 215;
gabbros of, 332, 349;
acid bosses of, 403;
acid sills of, 431;
pitchstone of, 445
Rutley, Mr. F., i. 131, 133, 170, 207, 210, 227, 231, 232, 238, 260; ii. 23, 35

Sahlite found in volcanic vents, i. 62
Saline Hill, volcanic vents of, i. 433, 435, 440
Sanday, basalts of, ii. 215;
conglomerates of, 226
Sandstone altered into quartzite, i. 72, 349, 350, 404, 432, 451; ii. 76, 164;
veinings of, in lava, i. 283, 300, 303, 320, 327, 333, 337; ii. 59, 98
Sandwich Islands, lava-cones of, i. 10
Sanidine ejected from volcanic vents, ii. 58, 79
Sanquhar, Silurian volcanic rocks at, i. 192, 195, 199;
Permian volcanic rocks at, ii. 62
Santorin, ii. 134
Saponite, ii. 79
Scenery, origin of, i. 8, 100
Schalstein, i. 262; ii. 36
Schists, primeval, i. 110, 114, 118, 119;
produced by deformation of igneous rocks, 75, 114, 118, 119, 121, 162, 240, 249, 252, 261
Schmidt, Dr. C. W., ii. 266
Scoriaceous structure, i. 15, 16, 282, 327, 339
Scorpions, fossil, i. 174, 356, 466
Scotland, lines of fault in, i. 11;
Vesuvian cones of, 42;
plateaux of, 43;
puys of, 46;
submarine lavas of, 48;
Carboniferous vents of, 55;
volcanic scenery of, 104;
pre-Cambrian rocks of, 111;
Cambrian rocks of, 112;
Lewisian gneiss of, 114;
Dalradian rocks of, 121;
Arenig rocks of, 123, 191;
Old Red Sandstone of, 266, 273, 281, 291;
Carboniferous geography of, 356;
Carboniferous volcanoes of, 359;
Carboniferous plateaux of, 367;
Carboniferous puys of, 414;
Permian volcanoes of, ii. 55;
Tertiary dykes of, 122;
Tertiary basalt-plateaux of, 208, 274, 304;
Tertiary gabbros of, 327;
Tertiary acid rocks of, 379
Scrope, G. P., i. 27, 82, 45, 116; ii. 373, 374, 381
Sedgwick, A., i. 142, 166, 175, 218, 227, 257; ii. 1, 2, 3, 5, 113, 139, 153, 157
Segregation (see Differentiation)
Segregation-veins, i. 84, 92; ii. 66, 130, 300, 303
Selwyn, Mr. A. C. R., i. 143, 175, 208, 221
Semi-opal, ii. 79
Sepulchre Mountain, i. 79
Serpentine, i. 195, 293
Shale, alteration of, i. 72, 451; ii. 164
Shap, granite of, i. 236, 238, 271, 290
Sheets, intrusive (see Sills)
Shelve, i. 176, 190
Shetland, i. 271, 289, 292, 293, 345
Shiant Isles, ii. 307
Shineton Shales, i. 144
Shore-lines, traces of ancient, i. 295, 305
Shropshire, ancient volcanic rocks of, i. 129, 189;
latest eruptive rocks of, ii. 101
Sicily, i. 26
Sidlaw Hills, i. 286, 294, 303
Sills, vitreous margins of, i. 18;
tectonic relations of, 77, 83, 451;
origin of name, 83;
differentiation (segregation) in, 81, 450; ii. 476;
ordinary stratigraphical position of, i. 85;
considered as parts of incompleted volcanoes, 86;
metamorphism by, 87, 94, 451; ii. 299, 303, 310;
conditions for injection of, i. 97, 98, 99, 458;
columnar structure of, ii. 187, 291, 301, 306, 308, 319;
amygdaloidal structure in, 299, 312;
banding of, 309;
split by later sills, 310, 316;
extreme subdivision of, 311;
slaggy surface in some, 312;
give off veins, 313;
double and multiple, 318, 434;
connection with vents, 322
—— pre-Cambrian, i. 118, 124;
Cambrian, 155, 170, 171;
Silurian, 187, 195, 206, 216, 237, 249;
Devonian, 261;
Old Red Sandstone, 277, 291, 321, 335, 343, 345;
Carboniferous, 408, 446, 472; ii. 2, 21, 30, 48;
Permian, 64, 66;
of Midlands, 102, 103;
Tertiary, (1) Basic, 298;
(2) Acid, 366, 430
Silurian system, i. 173;
vegetation of, 174;
geography of, 263;
volcanoes of, 175;
classification of, 175;
two volcanic series of, 177
—— volcanoes in Shropshire, i. 189;
in Scotland, 191;
at Builth, 203;
in Pembrokeshire, 205;
in Caernarvonshire, 207;
in the Berwyn Hills, 218;
in Anglesey, 219;
in the Lake District, 227;
in Gloucestershire, 238;
in Ireland, 239, 254
Skae, H. M., i. 294, 299, 306, 375; ii. 57
Skiddaw, i. 228;
granite of, 236
—— Slate, i. 229
Skomer Island, i. 207
Skye, spherulitic dykes and sills of, i. 20;
ophitic structure from, 20;
basalt-terraces of, 24;
metamorphism by granophyre of, 95, 96;
volcanic scenery of, 103, 105;
dykes of, ii. 123, 124, 129, 139, 140, 146, 150, 152, 154, 160, 162, 164, 165, 173, 269;
bedded basalts of, 192, 249, 269;
tuffs of, 251;
connection of dykes and superficial lavas in, 269;
vents in, 280;
sills of, 304;
gabbro bosses of, i. 116; ii. 334;
acid bosses of, 379;
acid sills of, 431;
acid dykes of, 437;
pitchstone veins of, 445;
subsidence of, 447
Slaggy structure, i. 16, 33, 59, 282, 327, 339; ii. 98, 187
Slane, volcanic rocks near, i. 244
Slate-tuffs, i. 180, 213, 234
Slemish a volcanic neck, ii. 271
Slieve Foye, ii. 421
—— Gallion, ii. 200
—— Gullion, ii. 422

Small Isles, basalt-plateau of, ii. 215;
vents of, 288;
sills of, 318;
acid bosses of, 403;
acid sills of, 431
Small, Mr. E. W., i. 207
Smaragdite found in volcanic vents, i. 62
Snowdon, volcanic rocks of, i. 20, 42, 47, 102, 175, 208, 209, 210, 211, 212, 213, 218, 226
Soda-felsites, i. 183, 196, 247
Solfataric action, i. 71; ii. 185, 205, 388
Sollas, Prof., i. 96; ii. 175, 293, 415, 421, 422
Solway, Carboniferous volcanic plateau of, i. 375, 385, 413
Somerset, volcanic rocks of, ii. 32
Somma, denudation of, i. 3, 100
Spheroidal structure of dolerite, i. 456
Spherulitic structure, i. 19, 20, 95, 120, 130, 155, 162, 184, 211, 232, 235, 346; ii. 369, 381, 392, 432, 435, 437, 441, 446
Spilosite, i. 262
Springs, mineral, connected with volcanic action, i. 390, 445
St. Abb's Head, i. 338
Staffa, i. 25;
first notice of, ii. 109;
columnar basalts of, 186, 188, 210;
basalt conglomerate of, 195
Staffordshire, latest eruptive rocks of, ii. 101, 103
St. Andrews, old volcanoes near, ii. 71, 73, 87
St. David's, Cambrian volcanic rocks of, i. 145
—— Head, i. 205
Steam in volcanic action, i. 13, 15, 16, 71
Stecher, Dr., i. 421, 451; ii. 165
St. Kilda, dykes of, ii. 173, 416;
gabbro of, 358;
general account of geology of, 405;
granophyre of, 408
Stocks, or bosses, i. 78, 88
Strahan, Mr. A., i. 171; ii. 10, 12, 23, 28, 32
Strathaird, ii. 123, 140, 164, 269
Strathbogie, i. 344; ii. 121
Strathmore, i. 304
Stromboli, i. 4
Sublimations, traces of ancient, i. 445
Submarine eruptions, i. 48
Sub-ophitic structure, i. 417
Subsidence and volcanic action, i. 295, 297, 444, 463; ii. 42, 205, 447, 470
Subterranean igneous injections, i. 77 (see Bosses, Dykes, Sills)
Suess, Prof. E., ii. 474
Sun-cracks, i. 342
Sweden, Archæan volcanic rocks of, i. 120
Syenite, ii. 366
Symes, Mr. R. G., i. 311, 343, 369; ii. 201, 428

Tate, G., ii. 3, 113
—— R., ii. 204
Tatlock, Mr. R. R., i. 273, 278
Tawney, E. B., i. 157
Teall, Mr. J. J. H., i. 90, 114, 116, 117, 118, 119, 120, 156, 192, 194, 200, 207, 210, 275, 277, 290, 311, 336, 338, 346, 407, 449; ii. 2, 3, 5, 7, 11, 32, 44, 113, 131, 134, 135, 137, 138, 140, 144, 149, 292, 293, 329, 367, 368, 369
Teesdale, i. 228
Termier, M. P., ii. 375
Terrestrial volcanic eruptions, i. 50
Tertiary Volcanic Series, ii. 181
Subaerial character of eruptions, ii. 103, 198
Scenery of, ii. 255, 256, 349, 391, 405, 408
The Plateaux, ii. 183, 249;
lavas of, 183, 218, 236, 256;
thickness of individual sheets, 192, 206, 254, 257;
lenticular character of lavas of, 193, 257;
greatest depth of, 210, 211, 213, 260;
tuffs and clays of, 194, 202, 204, 211, 222, 225, 251, 258, 277, 284, 287;
non-volcanic fragments in, 196, 211, 213, 219;
lignites of, 198, 203, 208, 213, 251;
gravels and conglomerates of, 198, 212, 238, 256;
coal of, 213, 251, 256, 287;
leaf-beds of, 204, 212, 222, 225, 288;
carbonaceous nature of the upper parts of intercalated sediments in, 223, 226, 227, 229, 232, 251, 288;
evidence for intervals between the eruptions in, 203, 205, 208, 221, 228, 240, 245, 251, 254, 288;
no evidence of great central vents in, 208, 214, 255, 258, 260, 267;
faulted condition of, 200, 208, 209, 452;
subsidences of, 205, 208, 209, 214, 447;
ancient river channels of, 217, 228, 231, 234, 456;
volcanic cones of, 202, 218, 230, 277, 281, 285;
paralleled by the modern Icelandic eruptions, 260;
vents of, 202, 218, 230, 270, 276
The Basic sills, ii. 298, 304
The Gabbro bosses, ii. 327, 349, 355, 358;
history of the gabbro intrusions, 359
The Acid rocks, ii. 364;
petrography of, 366;
history of their investigation, 371;
analogies with trachytes of Central France, 373;
intruded at base of the gabbros or of the bedded basalts, 337, 353, 357, 431, 432, 444;
bosses of Skye, 378;
of Mull, 395;
of Small Isles, 405;
of St. Kilda, 405;
of Arran, 418;
of Carlingford, 420;
of Slieve Foye, and Barnavave, 421;
of Slieve Gullion, 422;
of Antrim, 426;
acid sills, 430;
acid dykes and veins, 437
Metamorphism of the basalts, ii. 272, 276, 337, 339, 340, 347, 355, 356, 357, 358, 362, 378, 383, 386, 397, 399, 400, 404, 413
Texture, varieties of, in igneous rocks, i. 78, 449; ii. 5, 299, 360
Tholeiites, ii. 137, 158
Tholeiite type of basalt, i. 419, 421
Thornhill, volcanic rocks of, ii. 60
Thoroddsen, Th., ii. 261, 262, 263, 264, 265, 266, 278
Thrust-planes, i. 229
Time in geological history, ii. 107, 461, 465
Timmins, J. H., i. 133
Tinto, i. 278, 288, 329
Titterstone Clee Hill, ii. 101
Toadstones of Derbyshire, i. 359; ii. 8
Topley, W., i. 147; ii. 3, 5, 7
Torridonian rocks, i. 111, 112, 113, 120; ii. 350
Tortworth, volcanic rocks at, i. 238
Tourmakeady, volcanic rocks of Bala age at, i. 251
Townson, R., i. 363
Trachyte, i. 183, 230, 246, 273, 276 (analysis), 379 (analysis), 386, 403, 407, 421; ii. 36, 47, 96, 138, 152, 184, 236
Traill, Mr. W., ii. 175, 421, 422
Traprain Law, i. 372, 380, 403, 405
Traquair, Dr. R. H., i. 266
Tremadoc group, i. 144, 177
Trevelyan, W. C., ii. 3
Triassic eruptive rocks, i. 29;
geography, ii. 108
Trichites, i. 19; ii. 136